require "study_engine/assessment"
require "study_engine/config"

module StudyEngine
  class ExistingAssessmentsForm
    include ActiveModel::Validations
    extend ActiveModel::Naming

    def self.model_name
      ActiveModel::Name.new(Assessment)
    end

    validate :format_of_study_id
    validate :presence_of_some_event
    validate :presence_of_previous_events

    def initialize attributes = {}
      self.study_id = StudyID.new
      self.event_datetimes ||= []
      attributes.each do |name, value|
        send("#{name}=", value)
      end
    end

    def to_model
      self
    end

    def to_key
    end

    def persisted?
      false
    end

    attr_accessor :study_id, :method_applied, :event_datetimes

    delegate :study, :site, :id, to: :study_id, prefix: true
    delegate :study=, :site=, :id=, to: :study_id, prefix: true

    def method_applied
      @method_applied || "In-person"
    end

    def study_options
      StudyID::Bank.studies
    end

    def save
      if valid?
        base = Assessment.by_study_id(study_id)
        event_datetimes.each.with_index do |datetime, index|
          next if datetime.blank?
          event = StudyEngine.events[index]
          assessment = base.by_event(event).create!(created_at: datetime, assessment_updated_at: datetime, method_applied: method_applied)
          assessment.update_column :group_index, nil
        end
        true
      end
    end

    private

    def format_of_study_id
      if study_id.present?
        unless study_id.valid?
          errors.add :base, "METRC study ID must be in the following format: XXX-XXX-####"
        end
      else
        errors.add :base, "METRC study ID can not be blank.  Enter ID in the following format: XXX-XXX-####"
      end
    end

    def presence_of_some_event
      if event_datetimes.all?(&:blank?)
        events = StudyEngine.events.dup
        events.map!(&:downcase)
        events.last.prepend("or ")
        events = events.join(", ")
        errors.add :base, "A #{events} timestamp must be present"
      end
    end

    def presence_of_previous_events
      event_datetimes.each.with_index do |datetime, index|
        next if datetime.blank? || index.nil? || index.zero?
        event = StudyEngine.events[index]
        previous_events = StudyEngine.events[0...index]

        previous_events.each.with_index do |previous_event, index|
          if event_datetimes[index].blank? && Assessment.by_study_id(study_id).by_event(previous_event).none?
            errors.add :base, "Cannot add a #{event.downcase} assessment when #{previous_event.downcase} assessment does not exist"
          end
        end
      end
    end
  end
end